class Solution {
    public int uniquePaths(int m, int n) {
        int[][] res = new int[m][n];
        for (int i = 0; i < m; i++) {
            for (int j = 0; j < n; j++) {
                if (i > 0 && j > 0) {
                    res[i][j] = res[i - 1][j] + res[i][j - 1];
                } else {
                    res[i][j] = 1;
                }
            }
        }
        return res[m - 1][n - 1];
    }
}